Hum pot corrosion

mashaffer

Super Member
Given the tendency of pots to get wonky with time, especially when seldom moved, I wonder if hum pots have been a practical problem in that regard?
 
I've had a few fail open. I usually sub them with a pair of fixed resistors to fake a pot set in the middle and call it good. Most of the time they don't make very much difference unless you have AC phono heaters, and a better fix for that problem is DC phono heaters.
 
sometimes they will develop a spot where the metal between the movable contact and the base has corroded and formed some kind of oxide. If you break it free that spot will be noticeable when you rotate through its arc.
 
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